A modem (modulator / demonulator) is the device that converts the digital signals that computers produce to analogue signals that can be transferred over ordinary telephone lines.

Key details of modems -

• They may be on a card installed into the processor box, or external connected by a cable.
• The main variable is the maximum speed of transmission. The maximum today is 28.8kilobits/sec, although not all phone lines are usable at this speed.
• Always purchase the fastest modem you can afford - it will pay back in lower line costs.
• Prices for top end modems are in the range £85 - £160